Energy Nuclear SECURITY 7 March, 2022 9:00 am   
COMMENTS: Adam Rajewski

Rajewski: Nuclear shock during Russian invasion on Ukraine


Adam Rajewski from the Warsaw University of Technology, an expert on the nuclear sector, reassures about the seizure of the Zaporozhye nuclear power plant by the Russians during the invasion of Ukraine. “Ukraine is defending itself heroically, but it needs the support of Western countries. Thus, the Ukrainian government is quite understandably seeking to shock the Western governments and societies in order to urge them to provide more aid. That is understandable” he writes.

What happened?

The armed forces of the Russian Federation attacked the Zaporozhye Nuclear Power Plant. of The power plant was shelled, and as a result a fire broke out. According to available information, the fire occurred on the premises of facilities not related to technology – a training center and an administrative building. The fire was extinguished. Also, the building of reactor no. 1 received some light fire,, however no process systems important for maintaining nuclear safety were damaged. One of the six units of the power plant continued normal operation. The site itself is under the control of the occupying forces, and another power unit has been restarted recently. As of now, two power units remain in operation under control of their Ukrainian operators supervised by Russian military.

What could happen?

The situation, of course, raises questions from the category “what if the fighting continues” or ” what about other power plants.” There has been speculation on this issue for several days, with more or less ominous warnings coming from all sides, from the Ukrainian authorities, to the media, to the International Atomic Energy Agency. So let us sort out what we know.

All active nuclear reactors in Ukraine are pressurised water reactors. The worst that can happen to such a reactor is a disruption to its cooling system, both during operation and after a shutdown. If the reactor “looses” the coolant during operation as a result of a rupture of, for example, a cooling water pipeline, the chain reaction will break automatically –no water, no reaction (because water is also the moderator). But you need to keep cooling the core. All these power plants need electricity for this, but in addition to connections to the national grid and the possibility of using energy from other units at the same plant, they have their own emergency sources (diesel generators).

All reactors are installed in containment vessels, which protect them from various events outside, and the outside world from events inside. At Zaprorozhye, South Ukraine and Khmelnytski nuclear power plants, these enclosures are built as reinforced concrete bunkers, encompassing reactors with their complete cooling systems and most of their safety systems. Two reactors at the Rivne NPP have such a casing too, while two other have a simpler design. Bunkers of this kind can withstand a lot, including any accidental fire from small arms and probably from artillery. Once, during the construction of the Superphénix reactor in France, there was a terrorist attack, during which a very similar containment was fired upon with an RPG-7 anti-tank grenade launcher. Two missiles hit and caused only minor surface damage. These buildings exist to protect the systems inside from damage caused by natural occurrences, as well as by humans.

Of course, it is not like anything is indestructible. People have not invented indestructible structures, and once they came up with reinforced concrete, some other experts immediately started working on destroying it. So for sure there is a possibility to break through such a bunker, just like through any other. However, to the best of my knowledge, this would require targeted, specialist measures used in a very precise way. A tank cannon or an unguided missile is not enough. However, even breaking through the casing does not mean the reactor will blow up like in Chernobyl, but indeed in such a scenario the internal equipment may be damaged to some extent. Of course, people present on site can also damage stuff, if they choose to. This is why the IAEA has been sounding the alarm for many days that there is a possibility that nuclear safety will be compromised. Of course, there is. This is why international law forbids attacking such facilities, but we can all see how Russia treats international regulations.

Not every threat to nuclear safety is a threat even to the immediate environment, let alone an area as far away as Poland or any other country. On the contrary, nuclear facilities are designed so that this is not the case. Even a total destruction of some safety-related systems may not cause any measurable impact outside the containment, because these systems are both doubled (or more) – which is called redundancy, as well as layered (defence in depth). However, damage to parts of these systems is already classified as a quite serious safety violation.

Probably the most important thing from the Polish point of view is what is the worst that can happen? Well, if the containment is breached and some of the equipment inside is damaged, or in case of a very complicated and well-prepared sabotage, one could imagine that the cooling of the reactor will be disrupted. Then, after some hours or days (depending on when the reactor was last working), in the absence of cooling, part or all of the fuel may melt. Kind of like in Fukushima. Such an event can be accompanied by the production of hydrogen (in result of the fuel clads reacting with steam) – again, as in Fukushima. And this can (but in the case of a damaged and leaky building, it does not have to) lead to a smaller or larger explosion in the vicinity of the reactor. Ultimately, some radioactive substances may be released from the plant. Let me stress: we are already talking about a really unlikely course of events, which I cannot imagine without a well-planned targeted action. And in this situation, we are talking about a situation roughly comparable to Fukushima. That is, a measurable radiation hazard measured by a few kilometres around the power plant.

But should I be wrong about this, then there is still the time factor to consider. It takes hours for the fuel to melt after a serious damage to a reactor. It takes even more time for it to leak outside the building to occur. And then anything dangerous would still have to come all the way to Poland. It will be detected on the way. If not by Ukrainian radiation detection devices, then by Polish ones. Poland has a chain of radiation measuring stations along its eastern border. Poland also has a professional nuclear authority,the National Atomic Energy Agency (PAA). This institution has not been tainted by Polish mediocrity, perhaps with the exception of poor wages (which has also recently improved a lot). It issues announcements and reports on the measurements on an ongoing basis. It has already made announcements both on the situation at the power plant, and on radiation levels in Poland – these are, of course, normal.

Yes, I am aware that, according to media reports, President Zelensky said that an attack on nuclear power plants could pose a threat to the whole of Europe. And of course, I’m sure he knows a lot more about what is going on in these power plants than I do. But let us remember one thing. President Zelensky is the head of a state engaged in a very difficult defensive war in the face of a brutal assault by a more powerful neighbour. Ukraine is defending itself heroically, but it needs the support of Western countries. Thus, the Ukrainian government is quite understandably seeking to shock the Western governments and societies in order to urge them to provide more aid. That is understandable. But it also means that Ukraine is waging an information war for this purpose. Such messages are part of this war. Understandable, but not necessarily true. In this case, it’s not, although if I was where the Ukrainian government is now, I would probably be doing the same.